Mobile devices are typically powered by batteries, and the life of these batteries is determined by battery size and device's power consumption efficiency. In part to improve this efficiency, a mobile device often employs several switching regulators to efficiently convert a battery's energy into electrical power for use by other electronic components in the mobile device. Mobile devices can include mobile telephones, pagers, portable game consoles, and personal digital assistants, and the like.
A higher switching frequency is desirable in a switching regulator because it allows for the use of smaller value/size electronic components external to the regulator, such as inductors and capacitors, and can reduce the Electro-Magnetic Interference (EMI) interference in neighboring electronic components. The upper bound for switching frequency is generally limited by the efficiency requirements for the regulator. For example, as the switching frequency or input voltage increases, the transitional losses and gate charge losses to parasitic capacitances also increases in a relatively linearly dependent manner. In the past, these losses have made it difficult to achieve efficiency at relatively higher switching frequencies, especially for a relatively high input voltage, e.g., 12 volts, that is regulated with a relatively high switching frequency, such as 500 kilohertz.
To improve the efficiency of a switching regulator, the transitional losses can be reduced by reducing time taken for the power Field Effect Transistor (FET) to transition from on to off and off to on. However, the gate charge loss (energy required to charge and discharge the gate capacitance of the power FET for each cycle) is a fixed quantity for a given input voltage and switching frequency. On the other hand, if a substantial portion of the gate charge could be recovered each switching cycle, then the efficiency of a switching regulator could be made less dependent on its switching frequency. In other words, the switching regulator could operate at a higher switching frequency without the associated theoretical penalty in efficiency.